Pointing device

ABSTRACT

A pointing device is provided which can reduce its size and height, reduce leakage magnetic flux density to the outside. Magnetic sensors are disposed symmetrically two by two on X and Y axes on a printed circuit board. A silicone resin is placed on the printed circuit board, and an internally and externally unipolarly magnetized ring-like magnet is placed near the center of the magnetic sensors. The printed circuit board and silicone resin are not bonded. The silicone resin is easily deformed by applying external force, and returns to its initial state without the external force as soon as the external force is removed. The ring-like magnet is configured to move approximately in parallel to the surface of the printed circuit board. The variations in the ambient magnetic flux density produced by the movement of the ring-like magnet are detected by the magnetic sensors.

TECHNICAL FIELD

The present invention relates to a pointing device used as an inputmeans of a personal computer, mobile phone and the like, and moreparticularly to a magnetic detection type pointing device for carryingout coordinate detection or inputting vector information by detectingambient magnetic flux density variations due to the movement of amagnet.

BACKGROUND ART

FIG. 1 is a block diagram showing a magnetic detector circuit of aconventional magnetic detection type pointing device. A detectingsection 1 includes four magnetic sensors (such as Hall elements,semiconductor magneto-resistive elements, thin-film magneto-resistiveelements and GMR elements) 11, and the Hall elements 11 are placedsymmetrically two by two on the X and Y axes. A magnet is placed nearthe center of the four Hall elements 11 symmetrically disposed on the Xand Y axes. Because of the variations in the magnetic flux density dueto the movement of the magnet, the output voltages of the Hall elements11 vary.

Differential amplifiers 2 differentially amplify the outputs of the Hallelements 11 on the X and Y axes, respectively. The output is adjusted tozero when the magnetic flux density in the Z direction is symmetry withrespect to the origin O, that is, when the magnetized direction of themagnet is in the vertical direction. As the magnet moves, thedifferential amplifiers 2 produce outputs, and a detection controlsection 3 converts the outputs (analog values) in the X coordinate valueand Y coordinate value, which are output through an output controlsection 4.

As a concrete example of a small pointing device used by a mobile phone,a device is known which employs a scheme placing a magnet on a key mat.Such devices based on the method enable miniaturization among thecurrently proposed ideas (see Japanese patent application laid-open No.2002-150904, for example).

As a contact type pointing device, a device is common which forms on aprinted board two pairs of comb electrodes, and depresses them via aconductive rubber from the top to vary the current-passing state,thereby outputting coordinate values in digital values.

However, in small mobile electronic equipment such as a mobile phone,further reductions in size and height of the components are required tosatisfy mutually contradictory needs of reducing the size and improvingthe function of the electronic equipment in its entirety. In addition,further improvement in operating feelings of the magnetic detection typepointing device is expected.

Furthermore, as for the foregoing publication, since the magnet ismagnetized in the vertical direction, the magnetic flux density thatleaks out is large so that when a magnetic card is brought close to it,a problem of losing the information of the magnetic card is likely tooccur.

Moreover, since the input is made by depressing the conductive rubber inthe contact type pointing device, degradation of the conductive rubberinvolved in repetitive input and the like is unavoidable, which presentsa problem of reducing the life.

The present invention is implemented to solve the foregoing problems.Therefore it is an object of the present invention to provide a pointingdevice that can reduce the size and height, and provide a good operatingfeeling, and that has small external leakage of the magnetic fluxdensity, and has a long product life.

DISCLOSURE OF THE INVENTION

To accomplish the object of the present invention, there is provided apointing device characterized by comprising a ring-like magnet that ismovably supported in parallel to a plane; and a plurality of magneticsensors for detecting magnetic flux density produced by the ring-likemagnet in a direction parallel to the plane, wherein the magneticsensors detect variations in the magnetic flux density in the directionparallel to the plane, the variations being caused by movement of thering-like magnet.

The ring-like magnet is characterized by internally and externallyunipolarly magnetized.

The ring-like magnet is characterized by having at least one of itsinternal wall and external wall magnetized in a multipolar manner, andthe magnetic sensors are characterized by facing to a magnetic polecenter of the ring-like magnet magnetized in a multipolar manner.

The pointing device is characterized by further comprising a printedcircuit board on which a resin layer is provided, wherein the ring-likemagnet is fixed to the resin layer, and the magnetic sensors are placedon the printed circuit board.

The resin layer and the printed circuit board are characterized byhaving their opposing faces not bonded to each other.

The resin layer is characterized by being an elastic sheet.

The resin layer is characterized by being a silicone resin.

The magnetic sensors are characterized by being disposed symmetricallyon X and Y axes, which are two axes on a two dimensional plane of anorthogonal system, and the ring-like magnet is characterized by beingplaced near the center of the magnetic sensors.

The pointing device is characterized by further comprising a switch onthe resin layer side of the printed circuit board and at about thecenter of the ring-like magnet.

The pointing device is characterized by further comprising a projectionfor depressing the switch at a portion facing the switch on the resinlayer.

The magnetic sensors are characterized by being magnetic sensorsutilizing Hall effect, and outputting signals proportional to themagnetic flux density.

The magnetic sensors utilizing the Hall effect are characterized bybeing disposed on the resin layer side of the printed circuit board todetect the magnetic flux density in a direction parallel to the surfaceof the printed circuit board.

The magnetic sensors utilizing the Hall effect are characterized bybeing magnetic sensors with a single output terminal.

The magnetic sensors are characterized by being magnetic sensorsutilizing magneto-resistive effect.

The magnetic sensors utilizing the magneto-resistive effect arecharacterized by being semiconductor magneto-resistive elements whichare disposed on the resin layer side of the printed circuit board todetect the magnetic flux density in a direction parallel to the surfaceof the printed circuit board.

The magnetic sensors utilizing the magneto-resistive effect arecharacterized by being four semiconductor magneto-resistive elementsdisposed symmetrically on X and Y axes, which are two axes on a twodimensional plane of an orthogonal system, wherein two magnetic sensorson the X axis are electrically connected at a first connection point;and two magnetic sensors on the Y axis are electrically connected at asecond connection point, and wherein the pointing device detectsvariations in ambient magnetic flux density caused by movement of thering-like magnet using electric signals at the first and secondconnection points.

The pointing device is characterized by further comprising an originreturning means for returning the ring-like magnet to the origin usingmagnetic force generated by the ring-like magnet.

In addition, there is provided an electronic device incorporating theforegoing pointing device.

As the magnetic sensors, various types of magnetic sensors areapplicable such as Hall elements, Hall ICs, magneto-resistive elements(MR devices), magneto-resistive effect ICs (MRICs), and reed switches.Analog output type magnetic sensors are suitable for an analog outputtype pointing device, and digital output type magnetic sensors areappropriate for a digital output type pointing device.

When the Hall elements are used, it is preferable that they are disposedon the resin layer side of the printed circuit board, and detect themagnetic flux density in the direction parallel to the surface of theprinted circuit board to further reduce the size and height of thepointing device.

When the magnetic sensors utilizing the Hall effect are Hall ICs eachhaving a single output terminal, the number of the output signal linescan be reduced compared with the number of those using the Hallelements, thereby being able to save the space of the printed circuitboard, and to reduce the effect of external noise.

When the magnetic sensors utilizing the magneto-resistive effect areused, it is preferable that semiconductor magneto-resistive elements areemployed which are disposed on the resin layer side of the printedcircuit board, and detect the magnetic flux density in the directionparallel to the surface of the printed circuit board to further reducethe size and height of the pointing device.

In addition, it is also possible to dispose four semiconductormagneto-resistive elements symmetrically two by two on X and Y axes,which are two axes on a two dimensional plane of an orthogonal system;to electrically connect the two magnetic sensors on the X axis at afirst connection point; to electrically connect the two magnetic sensorson the Y axis at a second connection point; and to detect variations inambient magnetic flux density caused by the movement of the ring-likemagnet using electric signals at the first and second connection points.Such a configuration enables the reduction in the number of the outputsignal lines as compared with the case where the Hall elements are used.Thus, it can save the space for the printed circuit board, and reducethe effect of the external noise.

Furthermore, the switch can be placed on the resin layer side of theprinted circuit board. It is also possible to provide a projection fordepressing the switch onto the resin layer portion facing the switch.Although no restraint is imposed on the type of the switch, such aswitch is suitable which enables a user to confirm an object byutilizing physical contact with the object, such as tactile switch, pushbutton switch, tact switch, touch switch and stroke switch, which allowthe user to easily check pushing it (having tactile feedback), andautomatically returns after depressing the switch. Thus, the tactileswitch (also called dome switch) is preferable to reduce the size andheight.

As for the ring-like magnet, no restraint is imposed on its type. Thus avariety of ring-like magnet such as ferrite, samarium-cobalt, andneodymium based magnet which are usually mass-produced are applicable.To miniaturize the pointing device, it is essential to reduce the sizeof the magnet. Accordingly, a samarium-cobalt or neodymium ring-likemagnet which can produce intense magnetic field with a small body ispreferable. In addition, to reduce the height of the magnet, a bondedmagnet that is more easily molded is better than a bulk magnet. Theshape is not limited to the ring-like form as long as magnetized in thesame manner. Thus, cylindrical or prism-like shapes are also possible.However, using the ring-like magnet is preferable because this makes itpossible to suppress the total height of the pointing device even whenthe switch is mounted on the printed circuit board.

As the resin layer, a resin having elasticity is preferable. Although norestraint is imposed on the type of the elastic resin, a silicone resinthat is fit for a wide range of applications is preferable because it isinexpensive and easily available.

As for the ring-like magnet, it is preferable to construct it in such amanner that it produces the ambient magnetic flux density variationswhen moved in nearly parallel to the surface of the printed circuitboard because this enables further reduction in the height of thepointing device.

It is preferable that the opposing faces of the resin layer and theprinted circuit board are not bonded.

It is also preferable that the magnetic sensors are disposedsymmetrically on the X and Y axes, the two axes on the two dimensionalplane on the orthogonal system, and that the ring-like magnet be placednear the center of the magnetic sensors.

Besides, the origin returning means of the ring-like magnet can beprovided. Although fixing the ring-like magnet to the resin layer canmake one of such origin returning means, a magnet other than thering-like magnet can be added to construct a mechanism for returning tothe origin by utilizing the attractive force or repulsive force betweenthe two magnets.

The foregoing configuration enables the reduction in size and height,the reduction in the leakage magnetic flux density to the outside, andthe improvement in the operating feelings and in the product life. Thus,it can be suitably fitted to a variety of applications. Moreover,incorporating such a pointing device to electronic equipment can furtherreduce the size of the electronic equipment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit block diagram showing a configuration of a pointingdevice as a conventional example and as an example of a pointing devicein accordance with the present invention;

FIGS. 2A and 2B are views showing an embodiment of the pointing devicein accordance with the present invention;

FIGS. 3A and 3B are views showing another embodiment of the pointingdevice in accordance with the present invention;

FIGS. 4A and 4B are views showing still another embodiment of thepointing device in accordance with the present invention;

FIG. 5 is a view showing still another embodiment of the pointing devicein accordance with the present invention;

FIGS. 6A and 6B are schematic views showing a configuration of examples1 and 2 of the pointing device in accordance with the present invention;

FIG. 7 is a graph illustrating an output characteristic example of thepointing device with the configuration of the example 1;

FIG. 8 is a graph illustrating another output characteristic example ofthe pointing device with the configuration of the example 1;

FIG. 9 is a graph illustrating another output characteristic example ofthe pointing device with the configuration of the example 2;

FIG. 10 is a graph illustrating another output characteristic example ofthe pointing device with the configuration of the example 2;

FIGS. 11A and 11B are schematic views showing a configuration of anexample 3 of the pointing device in accordance with the presentinvention;

FIG. 12 is a graph illustrating an output characteristic example of thepointing device with the configuration of the example 3;

FIG. 13 is a schematic view showing a configuration of a conventionalpointing device; and

FIG. 14 is a graph illustrating output characteristics of theconventional pointing device as shown in FIG. 13.

BEST MODE FOR CARRYING OUT THE INVENTION

The embodiments in accordance with the present invention will now bedescribed with reference to the accompanying drawings.

A block diagram showing the magnetic detector circuit of the magneticdetection type pointing device in accordance with the present inventionis the same as the conventional circuit block diagram as shown inFIG. 1. Thus, the detecting section 1 has four magnetic sensors (such asHall elements) 11, and the Hall elements 11 are placed symmetrically twoby two on the X and Y axes. Close to the center of the four Hallelements disposed symmetrically on the X and Y axes, a ring-like magnetis placed. Because of the variations in the magnetic flux densityinvolved in the movement of the ring-like magnet, the output voltages ofthe Hall elements 11 vary.

The differential amplifiers 2 differentially amplify the outputs of theHall elements 11 on the X axis and Y axis, respectively. The magneticdetector circuit is configured such that the outputs of the X and Y axesare adjusted to zero when the ring-like magnet which is an internallyand externally unipolarly magnetized ring-like magnet is located on theorigin; that the differential amplifiers 2 have outputs in response tothe movement of the ring-like magnet; that the detection control section3 converts the outputs (analog values) to the X coordinate value and Ycoordinate value; and that the output control section 4 outputs them.

FIGS. 2A and 2B are views showing an embodiment of the pointing devicein accordance with the present invention: FIG. 2A is a top view; andFIG. 2B is a cross-sectional view taken along the line IIB-IIB of FIG.2A. In these figures, each reference numeral 11 designates a magneticsensor, the reference numeral 12 designates a ring-like magnet, 13designates a silicone resin, 14 designates a printed circuit board and15 designates a switch cover. The magnetic sensors 11 are disposed twoby two on the X and Y axes symmetrically on the printed circuit board 14as described above. The magnetic sensors 11 detect the magnetic fluxdensity in the direction parallel to the surface of the printed circuitboard 14.

Although the magnetic sensors 11 are placed outside the ring magnet 12in the configuration of FIG. 2A, they can be placed inside the ringmagnet 12. By thus placing the magnetic sensors 11 inside the ringmagnet 12, the pointing device can be further miniaturized. Thering-like magnet 12 is unipolarly magnetized in NS in the direction ofits radius. Which of the magnetization NS is to be placed outside is notlimited. In addition, the opposing faces of the silicone resin 13 andthe printed circuit board 14 are not bonded.

The silicone resin 13 is easily deformed by external force, and isreturned to its initial state without the external force by removing theexternal force. Thus, when the switch cover 15 is operated and moved insome direction, the ring-like magnet 12 moves in the same manner, andreturns to its initial state as soon as the external force is removed.Using the silicone resin 13 enables the miniaturization of the movingmechanism and the origin returning means.

As for the movement of the ring-like magnet 12, a configuration whichallows it to move in a direction approximately parallel to the surfaceof the printed circuit board 14 can reduce the height of the pointingdevice.

As for the fixing method of the ring-like magnet 12 to the siliconeresin 13, a simple method using an adhesive can be employed. In thiscase, it is preferable to bond them without applying the adhesive to theentire contacting face between the ring-like magnet 12 and the siliconeresin 13, but by applying to a portion except for portions close to theouter edge. This is because this makes it possible to effectively usethe elasticity of the silicone resin 13 and to increase the movablerange of the ring-like magnet 12. In addition, it is preferable that aconcave portion be provided at the mounting location of the ring-likemagnet 12 on silicone resin 13 because of a positioning problem of thering-like magnet 12.

As for the molding of the silicone resin 13, the insert molding ispossible to circumvent the need for bonding the ring-like magnet 12after the molding.

Replacing the ring-like magnet 12 and silicone resin 13 by a rubbermagnet enables further reduction in the height. The magnet can also beformed by mixing a magnetic material into part of the silicone resin 13.

In addition, comparing with a contact type pointing device, the magneticdetection type pointing device can increase its product life because itcan eliminate abrasion between components due to contact.

FIGS. 3A and 3B are views showing another embodiment of the pointingdevice in accordance with the present invention: FIG. 3A is a top view;and FIG. 3B is a cross sectional view taken along the line IIIB-IIIB ofFIG. 3A. It is a pointing device provided with a switching function byforming a concave portion in a silicone resin 23 corresponding to thesilicone resin 13 of the embodiment as shown in FIG. 2B, and byinstalling a switch 28 in the concave portion. In other words, it hasthe switch 28 on the silicone resin 23 side of the printed circuit board24. The silicone resin 23 has a projection 26 for depressing the switch28. Besides, the ring-like magnet 22 can reduce its height by using aneodymium bonded magnet.

Originally, although the pointing device is a device for outputting thecoordinate values of an input point, the switching function makes apointing device not only with the coordinate value output function, butalso with a deciding function. It has a configuration that achieves theswitching function by depressing the switch cover 25 in the direction ofthe ring-like magnet 22. Having the switch, it has two signals as amouse for a personal computer: the coordinate values and the decisionsignal.

As the switch 28, any switch including a push button switch can be used.However, such switches as a tactile switch, tact switch, touch switchand stroke switch are suitable which enable easy checking of depression(with tactile feedback), and return automatically after the depression,and which confirm an object by utilizing physical contact with theobject.

In addition, a gap 27 is formed by making the thickness of the siliconeresin 23 in and around the portion on which the ring-like magnet 22 ofthe embodiment as shown in FIG. 3B is mounted thinner than the thicknessof the portion of the silicone resin 23 on which the ring-like magnet 22is not mounted. The thinner the silicone resin under the ring-likemagnet 22, the greater the moving range of the ring-like magnet 22.Thus, it is preferable that the portion involved in the operation of thesilicone resin 23 be made as thin as possible.

FIGS. 4A and 4B are views each showing still another embodiment of thepointing device in accordance with the present invention. It has aconfiguration that replaces the internally and externally unipolarlymagnetized ring-like magnet in the embodiment shown in FIG. 3A by amagnet internally and externally magnetized in a quadrupole (FIG. 4A) oroctupole (FIG. 4B). Using the ring-like magnet 32 with the multipolemagnetization can enhance the converging effect of the magnetic flux andincrease the directivity. Thus the sensitivity of the pointing device isexpected to be increased. As for the number of poles of the ring-likemagnet 32, when it is set at an integer multiple of the number of themagnetic sensors 31, the magnetic sensors 31 can be opposed to the polecenters of the ring-like magnet 32 so that the high signal output isexpected. In addition, this makes it possible to share a signalprocessing section. Thus, the ring-like magnet 32 is preferablymagnetized at M poles (M=K×I, where K is the number of the magneticsensors used, and I is an integer equal to or greater than one).

Furthermore, even if the shape of the ring-like magnet 32 is changed toa solid cylindrical magnet, the outer surface of the magnet can bemagnetized in the same manner. When the present invention is carried outusing a magnet magnetized in multiple poles, a magnet with a shape otherthan a shape of a ring can also be employed.

FIG. 5 is a view showing still another embodiment of the pointing devicein accordance with the present invention. It has a configuration thatenhances the origin returning means of the ring-like magnet in theembodiment as shown in FIG. 2A. As described above, although thesilicone resin itself has a faculty for returning the ring-like magnet42 to the origin, the present embodiment has another magnet 49 insidethe ring-like magnet 42 to return the ring-like magnet 42 to the originutilizing the repulsive force between the two magnets. In the presentembodiment, the another magnet 49 is an internally and externallyunipolarly magnetized magnet provided with the S pole on its outersurface. With such a configuration, the degradation of the originreturning characteristic due to deterioration from aging of the siliconeresin can be prevented.

As for all the foregoing embodiments, it is supposed that the Hallelements are used as the magnetic sensors. Since the Hall elements havetwo output terminals each, the length of the output wiring increases.Thus, the wiring demands a large space and long distance, and hence thedevice is susceptible to external noise. However, using Hall ICs orsemiconductor magneto-resistive elements with a single output terminalas the magnetic sensors enables the reduction in the number of theoutput signal lines, thereby being able to save space of the printedcircuit board and to reduce the effect of the external noise.

In addition, all the foregoing embodiments assume the magnetic sensorsthat detect the magnetic flux density parallel to the surface of theprinted circuit board. However, magnetic sensors for detecting themagnetic flux density that makes an angle (between 0 to 90 degrees) withthe surface of the printed circuit board of less than about 60 degreescan offer similar advantages although the S/N of the pointing device isreduced.

Furthermore, as for the foregoing embodiments, since they employ thering-like magnet magnetized in the outer surface direction, it isexpected that the leakage magnetic flux density to the top surface ofthe switch cover be dramatically reduced. Thus, the problem of losinginformation of the magnetic card when it is brought close to the magnetcan be cleared up.

The present invention is not limited to the foregoing embodiments, butcan be modified in a variety of ways.

Next, concrete examples in accordance with the present invention will bedescribed.

Example 1

An example of the output characteristics will be described when thepointing device is constructed with the configuration of the foregoingembodiments in accordance with the present invention.

FIGS. 6A and 6B are views showing an example 1 of the pointing device inaccordance with the present invention: FIG. 6A is a top view; and FIG.6B is a cross sectional view taken along the line VIB-VIB of FIG. 6A.The ring-like magnet 52 has φ13 (external diameter)×φ8.8 (internaldiameter) and a thickness of 0.5 (all dimensions in mm). The ring-likemagnet 52 is internally and externally unipolarly magnetized, the outerside of which is the North pole, and the inner side of which is theSouth pole. As the ring-like magnet 52, a neodymium bonded magnet isused, the coercive force of which is 460 kA/m. The ring-like magnet 52is held movably in the z direction of FIG. 6B. The movable range of thering-like magnet 52 is ±1.2 mm in the z direction. The magnetic sensors51 are Hall elements that detect the magnetic flux density in the zdirection.

When the ring-like magnet 52 is placed at the origin, the distance fromthe external edge of the ring-like magnet 52 to the sensor position ofthe magnetic sensors 51 in the z direction is denoted by gapZ. Likewise,the distance from the center of the ring-like magnet 52 to the sensorposition of the magnetic sensors 51 in the x direction is denoted bygapX. In this case, the ring-like magnet 52 is moved in the z directionup to ±1.2 mm, and differences between the magnetic flux density of theright magnetic sensor 51 a and that of the left magnetic sensor 51 b arecalculated, the results of which are illustrated in FIG. 7. In thiscase, the gapZ is set at 2 mm, and the gapX is set at one of four values0 mm, 0.25 mm, 0.5 mm, and 0.75 mm.

It is found that the magnetic flux density variations equal to orgreater than ±20 mT take place when the gapX is set within 0.5 mm, andthe ring-like magnet 52 is moved up to ±1.2 mm in the z direction. Thevalues of the magnetic flux density variations are enough to be detectedby the Hall elements 51. In addition, it is also found that the magneticflux density variations increase as the gapX becomes closer to zero,which enables the pointing device to function more effectively.

Likewise, FIG. 8 illustrates the results of calculating the magneticflux density differences when the gapZ is 1.6 mm. Changing the gapZ from2 mm to 1.6 mm approximately doubles the values of the magnetic fluxdensity differences. From the foregoing results, it is found that as thevalues gapZ and gapX are made smaller, the characteristics of thepointing device are improved.

In addition, a particular advantage of the present example 1 of thepointing device is that when the ring-like magnet 52 approaches thelimit of the movable range (in the example, in a range where z is equalto or greater than +1.0 mm, or equal to or less than −1.0 mm), thepointing device has a large output. In other words, in a range where zis equal to or greater than 1.0 mm or equal to or less than −1.0 mm, theslopes of the graphs illustrated in FIGS. 7 and 8 increase.

For example, it is usual for a user who moves the cursor from a left endto a right end on a display to wish to move the cursor as quickly aspossible. In such a case, the user usually moves the ring-like magnet 52of the pointing device to the right end of the movable range. In thepointing device in accordance with the present invention, the cursormoves more quickly as it comes closer to the limit of the movable rangeof the ring-like magnet 52 (that is, the portions in which the slopes ofthe graphs in FIGS. 7 and 8 are large are utilized). Thus, it can besaid that the pointing device in accordance with the present inventionhas characteristics closer to the human feelings.

In contrast, the conventional pointing device has a problem in that themoving speed of the cursor is reduced as the magnet approaches the limitof its movable range (which will be described in a comparative exampledescribed later), and hence the operating feelings are deteriorated. Thepointing device in accordance with the present invention can eliminatethe foregoing problem, thereby being able to improve the operatingfeelings remarkably.

Although the magnetic sensors 51 are placed outside the ring-like magnetin present example 1, it is obvious that similar advantages are achievedeven if they are placed inside the magnet. In addition, placing theminside the magnet enables further miniaturization.

Example 2

Another example of the output characteristics will be described when thepointing device is constructed with the configuration of the foregoingembodiment in accordance with the present invention.

The main portion of the present example 2 is the same as the foregoingexample 1 as shown in FIGS. 6A and 6B. The ring-like magnet 52 hasφ11.78 (external diameter)×φ5 (internal diameter) and a thickness of0.485 (all dimensions in mm). The ring-like magnet 52 is internally andexternally unipolarly magnetized, the outer side of which is the Northpole, and the inner side of which is the South pole. As the ring-likemagnet 52, a neodymium bonded magnet is used, the coercive force ofwhich is 398 kA/m. The ring-like magnet 52 is held movably in the zdirection of FIG. 6B. The movable range of the ring-like magnet 52 is±1.2 mm in the z direction. The magnetic sensors 51 are Hall elementsthat detect the magnetic flux density in the z direction.

As in the example 1, when the ring-like magnet 52 is placed at theorigin, the distance from the external edge of the ring-like magnet 52to the sensor position of the magnetic sensors 51 in the z direction isdenoted by gapZ. Likewise, the distance from the center of the ring-likemagnet 52 to the sensor position of the magnetic sensors 51 in the xdirection is denoted by gapX. In this case, the ring-like magnet 52 ismoved up to ±1.2 mm in the z direction, and differences between themagnetic flux density of the right magnetic sensor 51 a and that of theleft magnetic sensor 51 b are calculated, the results of which areillustrated in FIG. 9. In this case, the gapZ is set at 0.7805 mm, andthe gapX is set at one of three values 3 mm, 2.5 mm and 2 mm.

It is found that only the magnetic flux density variations of about ±10mT at the most take place when the gapZ is set at 2 mm, and thering-like magnet 52 is moved up to ±1.2 mm in the z direction. Thevalues of the magnetic flux density variations are rather insufficientto be detected by the Hall elements 51.

To improve the pointing device with the foregoing configuration, themagnetic sensors 51 are replaced by those that detect the magnetic fluxdensity in the direction in the middle of the z direction and xdirection, that is, in the direction that makes 45 degrees with the zaxis direction and x axis direction, in which the magnetic flux densityfrom the ring-like magnet 52 is large. In the present example 2, themagnetic sensor 51 a detects the magnetic flux density in the lowerright direction, and the magnetic sensor 51 b detects the magnetic fluxdensity in the lower left direction. FIG. 10 illustrates the results ofcalculating the differences between the magnetic flux density of theright magnetic sensor 51 a and that of the left magnetic sensor 51 bwith moving the ring-like magnet 52 with the foregoing construction upto ±1.2 mm in the z direction.

It is found that the values of the magnetic flux density differences areapproximately doubled by replacing the magnetic sensors for detectingthe magnetic flux density in the z direction by the magnetic sensors fordetecting the magnetic flux density in the direction that makes 45degrees with the z direction. From the results, it is preferable thatthe detection direction of the magnetic sensors be changed appropriatelyin accordance with the positional relation between the ring-like magnet52 and the magnetic sensors 51 rather than limited to the z direction.However, as a guide of the detection direction of the magnetic fluxdensity of the magnetic sensors, it is known that good results areobtained by setting the angle with the z direction at about 60 degreesor less.

In addition, an advantage of the present example 2 of the pointingdevice is that when the ring-like magnet 52 approaches the limit of themovable range (in the example, in a range where z is equal to or greaterthan +1.0 mm, or equal to or less than −1.0 mm), the pointing device hasa large output. In other words, in the range where z is equal to orgreater than 1.0 mm or equal to or less than −1.0 mm, the slopes of thegraphs illustrated in FIG. 10 increase.

Although the magnetic sensors 51 are placed outside the ring-like magnetin the present example 2, it is obvious that similar advantages areachieved even if they are placed inside the magnet. In addition, placingthem inside the magnet enables further miniaturization.

Example 3

FIGS. 11A and 11B are views showing an example 3 of the pointing devicein accordance with the present invention: FIG. 11A is a top view; andFIG. 11B is a cross sectional view taken along the line XIB-XIB of FIG.11A, which show an example that replaces the internally and externallyunipolarly magnetized ring-like magnet 52 used by the example 1 by amultipolarly magnetized ring-like magnet 62. The ring-like magnet 62 hasφ12 (external diameter)×φ8 (internal diameter), and a thickness of 1(all dimensions in mm). The ring-like magnet 62 is magnetized inmultipolar fashion as shown in FIG. 11A. As the ring-like magnet 62, aneodymium bonded magnet is used. The ring-like magnet 62 is held movablyin the z direction and y direction. The movable range of the ring-likemagnet 62 is ±1 mm in the z direction and y direction, respectively. Themagnetic sensors 61 are Hall elements: those placed at the right andleft hand sides of the ring-like magnet 62 in FIG. 11A detect themagnetic flux density in the z direction; and those placed upper andlower sides of the ring-like magnet 62 detect the magnetic flux densityin the y direction.

When the ring-like magnet 62 is placed at the origin, the distance gapZfrom the external edge of the ring-like magnet 62 to the sensor positionof the magnetic sensors 61 in the z direction is set at 1.6 mm.Likewise, the distance gapX from the center of the ring-like magnet 62to the sensor position of the magnetic sensors 61 in the x direction isset at 0 mm. In this case, the ring-like magnet 62 is moved up to ±1 mmin the z direction and y direction, and differences between the magneticflux density of the right magnetic sensor 61 a and that of the leftmagnetic sensor 61 b are calculated, the results of which areillustrated in FIG. 12.

As in the example 1, good output characteristics of the pointing devicecan be confirmed. In addition, it is found that the characteristics ofthe pointing device are nearly independent of the position in the ydirection. It is also found that the slopes of the graphs increase atpositions close to the limit of the movable range of the ring-likemagnet 62, which enables the improvement in the operating feeling of thepointing device.

Although the present example 3 uses the ring-like magnet 62, it isobvious that similar advantages can be achieved by using a solidcylindrical magnet whose outer surface is magnetized in the same manner.Furthermore, although the present example 3 has the internal andexternal walls of the ring-like magnet 62 magnetized in a quadrupolemanner, this is not essential. For example, it is obvious that themultipolar magnetization other than the quadrupole magnetization canachieve similar advantages.

Comparative Example

Output characteristics of a configuration of a conventional magneticdetection type pointing device will be described.

FIG. 13 is a schematic diagram showing a configuration of a conventionalpointing device. A magnet 72 is a 3.9 mm square by 0.8 mm thick magnet.The magnet 72 is magnetized in the z direction as shown in FIG. 13. Asthe magnet 72, a neodymium sintered magnet is used. In addition, it isheld movably in the x direction and y direction in FIG. 13. The movablerange of the magnet 72 is ±1 mm in both the directions. The magneticsensors 71 are Hall device HQ8002 (trade name) of Asahi KaseiElectronics Co. Ltd., which includes four Hall elements in a singlepackage. The Hall elements are for detecting the magnetic flux densityin the z direction. In addition, the distance between the Hall elementsat the diagonal positions is 3.2 mm. FIG. 14 illustrates the measuredresults of the differences between the magnetic flux density of theright magnetic sensor section and that of the left magnetic sensorsection in HQ8002, when the magnet 72 is moved up to ±1 mm in the xdirection and y direction.

It is found that when the magnet 72 approaches the limit of the movablerange (when x is close to +1.0 mm or −1.0 mm in the example), the outputof the pointing device is reduced. In other words, when x is close to1.0 mm or −1.0 mm, the slopes of the graphs of FIG. 14 are reduced.

For example, it is usual for a user who moves the cursor from a left endto a right end on a display to wish to move the cursor as quickly aspossible. In such a case, the user usually moves the magnet 72 of thepointing device to the right end of the movable range. In the pointingdevice of the present comparative example, since the cursor moves moreslowly as the magnet 72 approaches the limit of the movable range (thatis, the portions in which the slopes of the graphs of FIG. 14 are smallare utilized), it is said that the pointing device has characteristicsdifferent from the human feelings. Thus, it deteriorates the operatingfeelings expected by the user, and hence the need for its improvement isundeniable.

In addition, the output characteristics vary depending on the positionin the y direction, which also impairs the operating feelings expectedby the user.

INDUSTRIAL APPLICABILITY

It is possible for the magnetic detection type pointing device toprovide good operating feelings, to reduce the size and height, toreduce the leakage magnetic flux density to the outside, and to lengthenthe product life. Thus, a pointing device can be provided which issuitably applicable to a variety of applications.

1. A pointing device comprising: a ring-like magnet that is movablysupported in a plane to move to various locations within that plane, andis magnetized such that said ring-like magnet comprises pairs of innerand outer ring sections of north and south magnetization that are bothin said plane and each pair of said north and south sections is at asame angle along a radius of said ring-like magnet; and a plurality ofmagnetic sensors for detecting magnetic flux density produced by saidring-like magnet in a direction parallel to said plane are placedoutside said ring-like magnet, wherein said magnetic sensors aredisposed symmetrically from each other to said ring-like magnet, andsaid magnetic sensors are positioned to detect variations in themagnetic flux density in the direction parallel to said plane, thevariations being caused by movement of said ring-like magnet in adirection parallel to said plane, wherein said inner ring sections areof both north and south magnetization such that inner ring sections ofnorth magnetization are placed in an alternative manner with respect toinner ring sections of south magnetization along an inner circumferenceof said ring-like magnet.
 2. The pointing device as claimed in claim 1,further comprising a printed circuit board on which a resin layer withelastic deformation is provided, wherein said ring-like magnet is fixedto said resin layer, and said ring-like magnet is movably supported inparallel to said printed circuit board, said magnetic sensors are placedon said printed circuit board.
 3. The pointing device as claimed inclaim 1, wherein said magnetic sensors are magnetic sensors utilizingHall effect, and the output signals are proportional to the magneticflux density.
 4. The pointing device as claimed in claim 1, wherein saidmagnetic sensors are magnetic sensors utilizing magneto-resistiveeffect.
 5. The pointing device as claimed in claim 1, further comprisingan origin returning means for returning said ring-like magnet to theorigin using magnetic force generated by said ring-like magnet.
 6. Thepointing device as claimed in claim 1, wherein said magnetic sensors aredisposed and faced to one of the outer ring sections of said ring-likemagnet.
 7. The pointing device as claimed in claim 2, wherein said resinlayer and said printed circuit board have their opposing faces notbonded to each other.
 8. The pointing device as claimed in claim 2,wherein said resin layer is an elastic sheet.
 9. The pointing device asclaimed in claim 2, wherein said resin layer is a silicone resin. 10.The pointing device as claimed in claim 2, further comprising a switchon the resin layer side of said printed circuit board and at about thecenter of said ring-like magnet.
 11. The pointing device as claimed inclaim 10, further comprising a projection for depressing said switch ata portion facing said switch on said resin layer.
 12. The pointingdevice as claimed in claim 3, wherein said magnetic sensors utilizingthe Hall effect are disposed on the resin layer side of said printedcircuit board to detect the magnetic flux density in a directionparallel to the surface of said printed circuit board.
 13. The pointingdevice as claimed in claim 3, wherein said magnetic sensors utilizingthe Hall effect are magnetic sensors with a single output terminal. 14.The pointing device as claimed in claim 4, wherein said magnetic sensorsutilizing the magneto-resistive effect are semiconductormagneto-resistive elements which are disposed on the resin layer side ofsaid printed circuit board to detect the magnetic flux density in adirection parallel to the surface of said printed circuit board.
 15. Thepointing device as claimed in claim 4, wherein said magnetic sensorsutilizing the magneto-resistive effect are four semiconductormagneto-resistive elements disposed symmetrically on X and Y axes, whichare two axes on a two dimensional plane of an orthogonal system, whereintwo magnetic sensors on the X axis are electrically connected at a firstconnection point; and two magnetic sensors on the Y axis areelectrically connected at a second connection point, and wherein saidpointing device detects variations in ambient magnetic flux densitycaused by movement of said ring-like magnet using electric signals atthe first and second connection points.
 16. An electronic deviceincorporating the pointing device as defined in any one of claims 1, 2,3-6, 7-9, 10, 11, 12, 13, 14, and
 15. 17. The pointing device as claimedin claim 1, wherein said ring-type magnet is magnetized at M sets ofnorth-south poles, where M=K×I, K equals the number of magnetic sensors,and I is an integer equal to or greater than one.
 18. A pointing devicecomprising: a ring-like magnet that is movably supported in a plane tomove to various locations within that plane, and is internally andexternally magnetized along said ring in said plane such that saidring-like magnet comprises inner and outer pairs of ring sections ofnorth and south magnetization that are both in said plane and each pairof said north and south magnetization that are both in said plane andeach pair of north and south sections is at a same angle along a radiusof said ring-like magnet; and a plurality of magnetic sensors whereinsaid plurality of magnetic sensors are positioned such that a distancefrom an intersection of half way between an upper and lower surface ofsaid ring-like magnet and a half way point of said magnetic sensors iswithin a range from 0 to 0.75 mm in a vertical direction to said plane,wherein said magnetic sensors are positioned to detect variations in themagnetic flux density in a direction parallel to said plane, thevariations being caused by movement of said ring-like magnet, whereinthe internal magnetization of said ring-like magnet contains sections ofnorth magnetization placed in an alternative manner with respect tosections of south magnetization along an inner circumference of saidring-like magnet.
 19. The pointing device as claimed in claim 18,wherein said magnetic sensors are magnetic sensors utilizingmagneto-resistive effect.
 20. The pointing device as claimed in claim19, wherein said magnetic sensors utilizing the magneto-resistive effectare four semiconductor magneto-resistive elements disposed symmetricallyon X and Y axes, which are two axes on a two dimensional plane of anorthogonal system, wherein two magnet sensors on the X axis areelectrically connected at a first connection point; and two magneticsensors on the Y axis are electrically connected at a second connectionpoint, and wherein said pointing device detects variations in ambientmagnetic flux density caused by movement of said ring-like magnet usingelectric signals at the first and second connection points.
 21. Thepointing device as claimed in the claim 18, wherein said ring-likemagnet is internally and externally unipolarly magnetized.
 22. Thepointing device as claimed in claim 18, wherein said ring-like magnet isinternally and externally magnetized in a multipolar manner in thedirection of its circumference, and said magnetic sensors are faced to amagnetic pole of said ring-like magnet magnetized in a multipolarmanner.
 23. The pointing device as claimed in claim 18, wherein saidmagnetic sensors are disposed symmetrically on X and Y axes, which aretwo axes on a two dimensional plane of an orthogonal system, and saidring-like magnet is placed near said magnetic sensors.
 24. The pointingdevice as claimed in claim 18, wherein said magnetic sensors aremagnetic sensors utilizing Hall effect, and the output signals areproportional to the magnetic flux density.
 25. The pointing device asclaimed in claim 24, wherein said magnetic sensors utilizing the Halleffect are magnetic sensors with a single output terminal.
 26. Thepointing device as claimed in claim 18, further comprising an originreturning means for returning said ring-like magnet to the origin usingmagnetic force generated by said ring-like magnet.
 27. The pointingdevice as claimed in claim 18, further comprising a printed circuitboard on which a resin layer with elastic deformation is provided, aswitch on the resin layer side of said printed circuit board and atabout the center of said ring-like magnet, and a projection fordepressing said switch at a portion facing said switch on said resinlayer.
 28. The pointing device as claimed in claim 27, wherein saidresin layer and said printed circuit board have their opposing faces notbonded to each other.
 29. The pointing device as claimed in claim 27,wherein said resin layer is an elastic sheet.
 30. The pointing device asclaimed in claim 27, wherein said resin layer is a silicone resin. 31.An electronic device incorporating the pointing device as defined inclaim
 18. 32. The pointing device as claimed in claim 18, wherein saiddistance in the vertical direction is within 0 and 0.5 mm.
 33. Thepointing device as claimed in claim 18, wherein said distance in thevertical distance is within 0 and 0.25 mm.
 34. The pointing device asclaimed in claim 1, wherein said outer ring sections are of both northand south magnetization such that outer ring sections of northmagnetization are placed in an alternative manner with respect to outerring sections of south magnetization along an outer circumference ofsaid ring-like magnet.
 35. The pointing device as claimed in claim 34,wherein said inner ring sections of north magnetization are placedopposite to said outer ring sections of south magnetization, and saidinner ring sections of south magnetization are placed opposite to saidouter ring sections of north magnetization.